Thanks, bahn - I'll lube the cable, that's all... I'm pretty confident that I know how fast I'm going since everyone else is usually going slightly faster !Sounds like lack of lubrication.....first step lube the cable...
Fwiw...i had a Bmw motometer do that after a instrument rebuild by the local VDO technician.. lubed the cable refitted it and the gauge died...lol .😄 . (Haha)
Could be lack of gease at the wheel end but sounds more like the gauge internals..
Leave alone unless confident in the job..